1. Field of the Invention
The present invention relates to a tilt control mechanism for use in an adjustable chair.
2. Brief Description of the Prior Art
In today's office environment, great emphasis is placed on worker comfort. To this end, designers are not only interested in the aesthetic look of office furniture, but also its functionality. One aspect of office furniture that has undergone great change is that of chairs.
Early designers of chairs were concerned more with aesthetic looks then functionality. Today there is a conscious blending of design and functionality to take into account many features including the general lumbar curve of the user, release of pressure points about the body, the ability of the frame to blend with the sitter, and the ability of the chair to accommodate the movements of the sitter with the chair conforming easily to a variety of body shapes.
Among features now incorporated into today's chairs are tilting mechanisms which allow the seat and back to tilt relative to a stationary base of the chair. There are many prior art examples of such arrangements.
U.S. Pat. Nos. 4,314,728 (Falks) and 4,494,795 (Roossien et al) are examples of chairs in which the chair back and the chair seat both tilt, and generally tilt together but at different rates. The back tilts at a faster rate so that as one tilts back, the user is less likely to have his feet lifted off of the floor by the rising front edge of the chair seat.
Other common types of chair controls include one attached to the seat only such that the chair and back tilt at the same rate or one attached to the back only such that the back tilts but the seat remains stationary.
U.S. Pat. No. 4,756,575 (Dicks) shows the use of springs in a frame assembly for a chair which has a backrest that is pivotal with respect to the seat of the chair.
U.S. Pat. No. 4,735,301 (Pergier et al) relates to a seat pitch adjustment assembly which a user can adjust upwardly or downwardly to limit the backward tilt of a chair seat.
U.S. Pat. No. 4,709,963 (Uecker et al) relates to an adjustable office chair to allow an adjustable tilt positioning of the backrest relative to the seat.
U.S. Pat. No. 4,720,142 (Holdridge et al) relates to a variable backstop provided for tilt back chairs, such as the type having a stationary support and a back which tilts with respect to the support.
All of these prior art examples permit backward tilting of a seat and chair back, either together, separately or together at differing rates. However, none of these chairs also include the ability to tilt a seat forward in the context of the same mechanism used to permit the seat to tilt backward.
There is thus a need for a chair tilt mechanism which permits forward and rearward tilting of a chair seat and a chair back in the context of the same mechanical mechanism. The present invention is directed toward filling that need.